The molding of overcaps for pressurized containers with integrally formed actuators designed to interact with a stem protruding from the top of the container to release the contents is well known. Such actuator-overcaps have an integrally formed fluid releasing channel that, at the inlet end, connects with the container stem. At the outlet end of the channel is usually inserted a spray forming nozzle which can have a swirl, flow restricting or nebulizing chamber as well as a discharge orifice. The chamber and orifice sizes and configurations are adjusted to provide the desired spray pattern and droplet size.
The usual method of formation of such an actuator-overcap nozzle assembly is to individually mold the actuator-overcap and the nozzle insert from thermoplastic material. Then, in a secondary assembly operation, the nozzle is pressed with interference fit into the outlet opening of the fluid releasing channel of the actuator-overcap.
This subsequent assembly step means that the two types of parts must be made, stored and handled, and then manually fitted together or fed to an assembly machine. The separate formation of the two parts also means that, unless all operations are conducted under controlled conditions, environmental conditions such as heat and humidity may differ between the formation of the actuator-overcap and the nozzle insert. Since the two are to be interference-fit together, tolerances are small, and minute variations in the behavior of the thermoplastic in the molding process may result in a larger proportion of non-secure fits.
Both problems--of labor and of control of conditions--would be solved by single step formation of the entire assembly. However, molding the actuator-overcap and nozzle insert as a single unit is not possible, due to molding technique restrictions. Simultaneous in-mold formation and assembly of the two parts would also solve the problems discussed above.
The integral molding of caps for dispensers having a plug portion attached to the cap portion is well known. U.S. Pat. No. 4,253,609 to Laauwe, "Dispensing Spray Nozzle", is of this type. The in-mold assembly of such articles is also known. U.S. Pat. No. 4,340,352 to Hayberg, "Hinge Exercising Mechanism," discloses a molding mechanism having a moveable finger which, after the cap-lid combination is molded, sweeps over the lid portion and snaps it into the cap portion.
A method of assembling and forming a delivery head and a break-up insert attached to the head by an attachment strip is disclosed in U.S. Pat. No. 4,741,088 to Ramella, "Method of Making a Delivery Head For Containers of Substances To Be Nebulized Having A Break-Up Plastic Insert Integrally Formed With The Head". When the mold parts separate, a mold fence first pushes against the attachment strip and swings it up against the head, forcing the insert into the outlet opening of the head, which is then stripped from the mold.